The present invention relates to solar fruit drying apparatus and more particularly to a solar fruit drying system specifically suited for large scale commercial drying applications which comprises a modification to my co-pending U.S. patent application Ser. No. 200,608, filed Oct. 24, 1980, and entitled "Improved Fruit Drying Device and Method of Drying Fruit."
It is long been known in the art to utilize solar radiation to dry fresh fruit, with the freshly picked fruit typically being layed upon a support surface and exposed directly to incident sunlight. In raisin production, for example, fresh grapes are layed upon a drying tray typically positioned between adjacent rows of grapevines within the vineyard and exposed to incident sunlight for a period of time (dependant upon weather conditions) sufficient to suitably dry the grapes into the desired raisin product.
With the advent of corporate farming in the United States large scale commercial production techniques have recently been developed to improve the production yield of dried fruit. With specific reference to raisin production, it is now common practice for large commercial vineyards to produce raisins by use of a "continuous" raisin production process. In this "continuous" process, a plastic coated paper sheet is rolled out upon the ground to extend between adjacent rows of grapevine throughout the length of the vineyard. Fresh grapes, either mechanically or hand picked from the vines, are deposited within a large hopper or accumulator which may be subsequently transported, as by way of a tractor, between adjacent rows of vines. As the hopper is transported between the rows of vines, it continuously deposits a uniform amount of grapes upon the paper tray sheet. Subsequently, the grapes are typically sprayed with a pre-drying chemical compound which promotes extractions of moisture from the grapes; and after a period of exposure to sunlight, the resultant raisin product may be packaged, and marketed to the consumer. Although this "continuous" raisin production process has proven to reduce overall labor costs associated in raisin production, there exists substantial deficiencies associated in its use.
Foremost of these deficiencies, is the exposure of grapes during the drying process to moisture such as by rain or dew, as well as to birds and other animal predators. Excessive moisture accumulating on the grapes during the drying process typically results in decay or mold forming on the grapes which is substantial, often renders the entire raisin crop unedible. Similarly, bird and animal predators often reduce crop yield by significant scavenging and further leave droppings and other debris which pose a health hazard to the ultimate consumer. In addition, the use of the pre-drying chemical sprays, although promoting more rapid fruit drying, typically break the skin of the grapes and reduce the quality of the final raisin product.
Although these above deficiencies have been recently recognized in the art, the proposed solution to date has been the use of a thin, flexible polyethylene sheet which is layed directly over the paper sheet and grapes and affixed to the soil. Although the use of such sheet coverings has partially reduced the susceptibility of the dried fruit to be exposed to moisture, it adversely effects the overall production costs of the raisin yield by requiring substantial labor costs to be expended during installation in the growing field. Additionally, such flexible sheet covering are susceptible to damage by strong winds and animal predators. Further, such sheet coverings rapidly degrade upon exposure to ultra-violet radiation which renders them unacceptable for multiple or consecutive drying applications.
Hence, there exists a substantial need in the art for a fruit drying system which is specifically adapted for large scale "continuous" raisin production applications, which safeguards against damage to the crop caused by moisture, birds and animals and may be utilized without significantly affecting labor costs, may be reused on consecutive crops from growing season to growing season, and may effectuate rapid and consistent fruit drying without the use of external artificial heat energy.